Electrolytic electrocopying apparatus



DeC- 5, 1951 E. G. JOHNSON ETAL 3,011,963

ELECTROLYTIC ELEcTRocoPYING APPARATUS Filed Sept. 25, 1957 fHfAf@ Edgar G. Johnson,

United States Patent iihce 3,011,953 Patented Dec. 5, 1961 3 011 963 ELEcTRoLYrrc ELErRC'oPYING APPARATUS St. Paul, Minn., and Byron W. Neher, Hudson, Wis., assignors to Minnesota Mining and Manufacturing Company, St. Paul, Minn., a corporation of Delaware Filed sept. 25, 1957, ser. No. 686,237 4 Claims. (ci. 20s-206) This invention relates to the reproduction of visible images by electrolytic electrocopying, and has particular reference to novel combinations of apparatus employed therein. While not restricted thereto, the invention relates in one highly important commercial aspect to apparatus suitable for the rapid scanning and electrolytic electrocopying of information stored in the form of microlm copies, and for convenience will be described principally in terms of such exemplary embodiment.

This application is in the nature of a continuation-inpart of the co-pending Johnson et al. application Serial No. 575,070, tiled March 30, 1956.

Microlrning of documents permits the storage of enormous amounts of information in relatively small space and the rapid scanning of such information. In many cases, however, it becomes desirable to provide a copy of the original page or document in printed form. The present invention provides means for scanning microlilmed documents and for reproducing any desired frames in enlarged printed form for vconvenience in further study. Reproduction is completed within the time normally required for inspection of the next succeeding frame, and the printed copy is ready for immediate handling or tiling.

. In the drawing,

FIGURE 1 is a simplified representation in section of one modification of a microfilm reader and copier embodying the principles of the invention;

FIGURE 2 is a front elevation of the apparatus of FIGURE l;

FIGURE 3 is a diagram of a typical circuit employed in the apparatus of FIGURE l;

FIGURES 4 and 5 represent modifications of the print developing and advancing means of the apparatus of FIGURES 1 and 2; and

FIGURE 6 is a schematic illustration of an alternative type of apparatus useful in electrolytic electrocopying-of light-images.

The apparatus of FIGURES l and 2 consists of a case having an upper portion 10 and a lower portion 11. The lower portion contains means for providing a series of light-images, which as illustrated include a lamp 12 within a housing 13, a condensing lens system 14, and an enlarging lens system 15. The microfilm 16 is supported in position in the light beam by known guide means not shown, and is advanced from supply roll 17 to windup reel 18 by suitably turning the handle member 19.

The upper portion 10 is provided on the front panel with a ground-glass viewing screen 21, a milliarnmeter 22., and a rheostat 23. A lever 24 controls the position of a reflective panel 25 which pivots around an axis 26 and between the internal panel members 27 and 28. A supply roll 29 of photosensitive copy-paper 30 is supported on a spindle 31. The copy-paper passes across the open area between a control roller 32 and an exit slot 33, being supported along both edges by flange members 34, and held in contact with a porous sponge-like applicator pad 35 by means of a spring member 36, the pad and spring extending across the full Width of the paper and acting as a barrier against light entering through the slot 33. The applicator pad is supported in a reservoir 37. A source of current such `as batteries 38 is connected in series with a switch Ztl and with rheostat 23, pad 35, ammeter 22 and sensitive paper 30, as shown in detail in FIGURE 3. Connection is made to the pad '35 through the reservoir 3'7 and to the sensitive paper St) through the spindle 31 to which the conductive backing of the copypaper is connected.

In operation, the reflective panel 25 is swung, by means of the handle 24, to the open position indicated by dotted lines 25a and the microiilm 16 is advanced frame by frame, by means of handle 19, until the desired frame is projected on the screen 21. The panel 25 is then moved to the closed position shown, thus acting as a shutter and permitting the light-image to fall on the active surface of the sensitive copy-sheet 30. After a suitable interval, the panel 25 is returned to position 25a, the switch 20 is turned on, and the image-bearing portion of the copy-sheet 3@ is drawn from the casing through the slot 33, the sensitive surface meanwhile uniformly `contacting the pad 35 which is continuously moistened with solution from the reservoir 37. The image is developed on the copy-sheet by electrolytic action at the contact area. The fully developed print is detached near the slot opening, and the apparatus is in readiness for further use.

It has been found that a fully developed enlarged copy of a microfilm frame may be produced by the abovedescribed procedure within a total time of not greater than about live seconds, which is normally less than the time required for visual scanning of the next succeeding frame of the film. The print is pro-duced in substantially dry condition and may be handled, folded, or filed without dihculty.

Hand operation as just described will produce acceptably uniform copies when care is taken to draw the print from the apparatus at uniform predetermined speed. 'Ihe apparatus may alternatively be provided with automatic means for accomplishing the several steps involved in the order and at the rate required. FIGURES 4 and 5 illustrate typical mechanisms by which the copypaper may be mechanically advanced.

=In FIGURE 4, a lower roll 40 rotates freely in a reservoir 41 containing the electrolyte, and an upper roll 42, mechanically driven by means not shown, presses the exposed ycopy-paper 30 against the lower roll and advances the paper through the exit slot 43. The roll 40 replaces the pad 35 in the circuit of FIGURE 3, and electrolysis is accomplished at the surface of the copypaper at the contact area. The amount of solution remaining on the paper is limited by the wringer action of two rolls, which conveniently are provided with compressible rubber surfaces. Ceramic or other rolls will also effectively transfer the solution to the copy sheet, current being transmitted-through the layer of solution on the roll surface. A metal roll, used with a suitable electrolyte, may itself serve as a source of metal ions to be transferred to the copy-paper surface. Rollsor belts surfaced with gelatin or the like, plasticized with glycerine or other humectant, and toughened slightly with formaldehyde or other curing agent if desired, are particularly useful. Such rolls and sheets are well known in the form of inking rollers and hectograph pads. Suitable dry salts may be included in the copy-sheet and the moisture present in the gelatin roll, together with such salts, provides the required electrolyte. Salts and other ionizable impurities in the roll ordinarily provide sutlcient conductivity to permit electrolysis at the surface of the copy-sheet, or such materials may be added if necessary. More particularly, the complete electrolyte may be incorporated in the roll. The humectant serves to maintain a suicient content of moisture for electrolysis. In such cases the trough 41 of FIGURE 4 may be eliminated. The roll carrying the electrolytic developer is directly connected into the electrical circuit through its conductive shaft, and is replaced when the electrolyte content is depleted. The smooth-surfaced hydrophilic electrolyte-permeable roll or belt thus serves both as an electrode and as a reservoir for lthe electrolytic develop er material.

In FIGURE a brush 51 replaces the pad 35 of FIGURES l and 3 and also serves to hold the copy-sheet Si) against the 'guide 56, which replaces spring 36 of FIGURE 1.V The copy-sheet 50 is in this case provided with edge sprocket-holes and is advanced through slot 53 and past guide member 52 by sprocket Wheels 54, mechanically driven by means not shown. Alternatively the sprocket wheels may be provided with sharp pins in place of `gear teeth, the pins penetrating the edge areas of copy-paper and making electrical contact with the conductive backing, inwhich case no contact is required between backing and shaft 31. At the conclusion of the cycle, the print is cut from the supply sheet 30 by a shear blade 55 operating against an edge of guide 52 as illustrated.

It will be appreciated that the specific components and arrangements employed in the device of FIGURE 1 for impressing the light-image upon the sensitive sheet may equally well be replaced by various other image-forming systems, including, for example, reection from an original as in photographic or Photostat processes, contact printing as in the making of blue-print or photographic positives, scanning with a modulated moving beam, and image formation through application of X-rays and electron beams. of copy-paper there may be used individual sheets or cards, contact with the conductive backing thereof being made as in the modication of the apparatus of FIGURE 5 previously described, or in other Ways, `during the developing operation.

A simplied form of apparatus is illustrated in FIG- URE 6. Light from a lamp 69 passes through a negative transparency 61 and a lens system 62 to produce a light-image which -is transmitted through the transparent Likewise, in place of continuous rolls wall 63 of the tank 64, through the eletcrolyte 65, and

through the open frame electrode 66, to the yphotoconductive Waterproof surface 67 of the copy-sheet 68. The

Vconductive carrier or backing component 69 is connected in series with a switch 70, battery 71, rheostat 72, ammeter 7.3, andl thence to the electrode 66. The edges and back surface of the copy-sheet 68 are protected from conductive contact with the electrolyte 65, and the assembly is protected from extraneous light, by means not shown. Closing the switch 70 causes the rapid formation of a visible reproduction rof the light-image on the surface of the sheet 68.

An effective copy-paper for use in apparatus as hereinbefore described and illustrated consists of a laminate Vof paper and thin aluminum foil coated on the clean rei'iective metal surface with a smooth, uniform, strongly photoconductive layer of powdered inorganic Water-insoluble photoconductor and ilexible water-resistant resinousinsulating binder.' A mixture of four parts by weight of USP-l2` French process zinc oxide and one part of water-resistant insulative binder'suich as Pliolite S-7,.a copolymer of about 30 parts butadiene and measured thickness of the Ycoating Vunder an appliedY Y voltage both under equilibrium dark 'conditions and when illuminated. A potential offlU'volts is convenientV of the coating is conveniently deterj but not critical. Values at several thicknesses may be determined and the value at a standard thickness obtained by interpolation. At 10 volts potential and 0.8 mil thickness of coating, a copy-paper prepared as just described was found to have a dark conductivity of the order of 5x10-9 mho/cm. When illuminated for 5 seconds with light from a SOO-watt incandescent-filament lamp, i.e. at an intensity of about 1300 foot-candles, its conductivity increased to about l.8-2.2 l0"-6 mho/cm.

After exposure to light, the conductivity of the photoconductive surface of the copy-sheet just described decreases rapidly inthe dark,` but retains sufficient conductivity for suiicient time to permit subsequent development in the apparatus and by the procedures describedl -in connection with FIGURES 1-5. As an example, a copy-sheet Which exhibited a conductivity of 2.l l'0"6 mho/cm. when illuminated for ve seconds was found to be reduced in conductivity to a value of Y 1.5 X10-6 mho/cm. at three seconds, and 1.05 l0-s mho/cm. at fourteen seconds, after cessation of illumination. The length of time for exposure and development is regulated to provide a low rate of decay ofk conductivity in the light-exposed portions while maintaining an adequately high level of conductivity for proper electrolytic action in the time available. The time schedule is preferably automatically controlled by means of preset timing mechanisms in apparatus such as that of FIGURES 4 and 5, but effective results may consistently be obtained onrmanual operation of the apparatus of FIGURES land 2 by capable operators.

Electrolytic developmentV of light-struck areas is conveniently accomplished with an electrolytic developer material containing metal ions. Solutions of copper sulfate and of silver nitrate have been found useful, as has a solution containing 10% nickelous chloride and 5% sodium thiosulfate. A preferred developer solution for application with a pad or sponge as described in connection with FIGURE 1l contains 3 parts by weight of cadmium nitrate tetrahydrate, 0.5 part each of k'tartar emetic and silver nitrate, and parts of Water. The electrolytic developer material may be applied in bulk form as in FIGURE 6, or as a thin coating as in FIG- URES 1, 4 or y5. An electrolytic'ideveloper material may also be provided `by applying Water to a sensitive surface containing the desired developer salts or other materials in dry form, as hereinbefore described in connection with FIGURE 4.

Other electrolytic developer materials have Ibeen provided which produce useful visibleY images by oxidation of leuco dye, by electrodeposition of dispersed colloidal organic materials, or in various other ways, although best results have thus far been attained by'electrodeposition from electrolytic developer material in the form of aqueous solutions containing metal ions. The copies are useful ofthemselves, and in addition are useful in making additional copies 'by other duplicating processes. Thus, a copy produced by elect-rodeposition from a solution, at pH 6, of nickel ammonium sul-fate electrolytic developer material on light-exposedconductive areas of a Zinc oxide copy-paper has been shown to be eifective as a printing plate for lithographie oifset printing. The image areas and the bare oxide background areas' have opposite wetting tendencies toward aqueous fountain solutions and non-aqueous ink compositions. Analogously, copy produced by electrolysis of an electrolytic developer material based Ona soluble dyestuA has been found to have dye-containing image areas from-which the dye-Y stuff .is *transfer-abile, in Vthe presence of small'amounts of a suitable volatile solvent, to paper. The duplication by these land otherV` direct printing methods Vofelectrolytically developed origina-ls produced `as hereinbefore described has important application in the photocopying and photographic art.` Thus,',there is madepossible a photographic apparatus with which any desired number of printed positive copies may be ydirectly produced immediately after exposure to the desired light-image.

Successful application of the apparatus of FIGURES l-5 requires that the photoconductive copy-paper possess suicient light-memory to provide an adequately high level of conductivity vat least a few seconds after completion of a brief exposure to the light-image. Apparatus embodying the principles of that of FIGURE 6 is preferred for use with copy-papers having too short a light-memory for such applications. Here the lightimage is formed and developed simultaneously, so that no light-memory is required. However it is also true that relatively large volumes of electrolyte are required, and the solution ordinarily causes some absorption and scattering of the light, and the copy-paper may absorb excessive amounts of liquid. -It is therefore preferred to use copy-paper having a reasonable degree of lightmemory, and to carry out the electrolytic development step subsequent to the exposure step, eg. in apparatus as described in connection with FIGURES 1-5.

While the invention has been described primarily with relation to the copying of microfilm, it wil-l be seen to be equally well adapted to a wide variety of specifically different but generally related operations. Copies of printed books or papers, drawings or blueprints, sketches, paintings, or any other `form of graphic original are conveniently produced. Color separations are possible by employing suitable filters. Where sutiiciently sensitive photoconductive sheet material is provided, direct photographs are made possible, and from these further copies may -be produced in a variety of Ways. By proper selection of back-ground and electrolytic developer material, light-struck areas are easily developed in either darker or lighter tone than the contrasting background, so that either positives or negatives are provided as desired.

What is claimed is as follows:

l. Apparatus `for electrolytically reproducing an image which comprises in combination an enclosed container having an elongated opening for removal of la reproduction sheet from within said container and having an aperture in one end of said container, an enlarging lens adjacent to said aperture, means for directing a beam of radiation through said enlarging lens and said aperture whereby said radiation is projected to the other end of said container to form a projection area, means positioned within said container for supporting a roll of photoconductive copy sheet, means positioned within said container for receiving and positioning a portion of said photoconductive copy sheet across the end of said container to which said light is projected and directing said copy sheet through said elongated opening, an electrode positioned within said enclosed container between the projection area of the container and said elongated opening and adapted to electrolytically contact the exposed portion of said photoconductive copy sheet, means for passing the exposed portion of said copy sheet across said electrode and in electrolytic contact therewith whereby electrolytic development is effected at said electrode,

and means for connecting an electrical potential between said electrode and said photoconductive copy sheet.

2. Apparatus for viewing and electrolytically printing a microfilm which comprises in combination yan enclosed container having an elongated opening for Iremoval of a reproduction sheet lfrom within said container and having an aperture in one end of said container, an enlarging lens adjacent to said aperture, means for directing a beam of 4light through said enlarging lens and said aperture whereby said light is projected to the other end of said container to `form a projection area, means for supporting a roll of microfilm and continuously passing the microfilm between said light source vand said lens, a spindle positioned within said container for supporting a roll of photoconductive copy sheet, support means positioned within said container for receiving and positioning a portion of said photoconductive copy sheet across the end of said container to which said light is projected and directing said copy sheet through said elongated opening, an electrode positioned within said enclosed container between the projection yarea of said container and said elongated opening and adapted to electrolytically contact the exposed portion of said photoconductive copy sheet, a ground-glass viewing screen forming at least a portion of one side of said enclosed container, a pivoted reflective surface member positioned within said container and adapted to pivot in front of said viewing screen away from the path of said light projection and to pivot into a position in the path of said light projection to reflect light from said light source onto said viewing screen, means for passing the exposed portion of said copy sheet past said electrode and in electrolytic contact therewith lwhereby electrolytic development is effected at said electrode, and means for connecting an electrical potential between said electrode and said photoconductive copy sheet.

3. The apparatus of claim 2 in which said electrode contains, and is permeable to, an electrolytic developer material.

4. The apparatus of claim 3 in which said electrode comprises in combination therewith gelatin and a humectant plasticizer therefor.

References Cited in the tile of this patent UNITED STATES PATENTS 1,894,004 Rose Ian. 10, 1933 2,540,602 Thomas et al. Feb. 6, 1.951 2,636,848 Greig Apr. 28, 1953 FOREIGN PATENTS 464,112 Great Britain Apr. l2, 1937 894,125 France Dec. 14, 1944 151,971 Germany Dec. 28, 1902 OTHER REFERENCES Television, published by the Experimental Publishing Co., vol. 1, No. 1, June 1928, page 20. 

1. APPARATUS FOR ELECTROLYTICALLY REPRODUCING AN IMAGE WHICH COMPRISES IN COMBINATION AN ENCLOSED CONTAINER HAVING AN ELONGATED OPENING FOR REMOVAL OF A REPRODUCTION SHEET FROM WITHIN SAID CONTAINER AND HAVING AN APERTURE IN ONE END OF SAID CONTAINER, AN ENLARGING LENS ADJACENT TO SAID APERTURE, MEANS FOR DIRECTING A BEAM OF RADIATION THROUGH SAID ENLARGING LENS AND SAID APERTURE WHEREBY SAID RADIATION IS PROJECTED TO THE OTHER END OF SAID CONTAINER TO FORM A PROJECTION AREA, MEANS POSITIONED WITHIN SAID CONTAINER FOR SUPPORTING A ROLL OF PHOTOCONDUCTIVE COPY SHEET, MEANS POSITIONED WITHIN SAID CONTAINER FOR RECEIVING AND POSITIONING A PORTION OF SAID PHOTOCONDUCTIVE COPY SHEET ACROSS THE END OF SAID CONTAINER TO WHICH SAID LIGHT IS PROJECTED AND DIRECTING SAID COPY SHEET THROUGH SAID ELONGATED OPENING, AN ELECTRODE POSITIONED WITHIN SAID ENCLOSED CONTAINER BETWEEN THE PROJECTION AREA OF THE CONTAINER AND SAID ELONGATED OPENING AND ADAPTED TO ELECTROLYTICALLY CONTACT THE EXPOSED PORTION OF SAID PHOTOCONDUCTIVE COPY SHEET, MEANS FOR PASSING THE EXPOSED PORTION OF SAID COPY SHEET ACROSS SAID ELECTRODE AND IN ELECTROLYTIC CONTACT THEREWITH WHEREBY ELECTROLYTIC DEVELOPMENT IS EFFECTED AT SAID ELECTRODE, AND MEANS FOR CONNECTING AN ELECTRICAL POTENTIAL BETWEEN SAID ELECTRODE AND SAID PHOTOCONDUCTIVE COPY SHEET. 